[PATCH v4 3/4] drm/virtio: add in/out fence support for explicit synchronization

[Gerd Hoffmann]

On Mon, Nov 12, 2018 at 11:30:57AM +0100, Robert Foss wrote:
> Hey Gerd
> 
> On 2018-11-12 10:10, Gerd Hoffmann wrote:
> > On Fri, Nov 09, 2018 at 06:13:52PM +0100, Robert Foss wrote:
> > > Hey Gerd,
> > > 
> > > On 2018-11-09 11:13, Gerd Hoffmann wrote:
> > > > On Mon, Nov 05, 2018 at 05:25:05PM +0000, Emil Velikov wrote:
> > > > > On Mon, 5 Nov 2018 at 11:42, Robert Foss <robert.foss at collabora.com> wrote:
> > > > > > 
> > > > > > When the execbuf call receives an in-fence it will get the dma_fence
> > > > > > related to that fence fd and wait on it before submitting the draw call.
> > > > > > 
> > > > > > On the out-fence side we get fence returned by the submitted draw call
> > > > > > and attach it to a sync_file and send the sync_file fd to userspace. On
> > > > > > error -1 is returned to userspace.
> > > > > > 
> > > > > > Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.com>
> > > > > > Signed-off-by: Robert Foss <robert.foss at collabora.com>
> > > > > > Suggested-by: Rob Herring <robh at kernel.org>
> > > > > > Reviewed-by: Emil Velikov <emil.velikov at collabora.com>
> > > > > > ---
> > > > > > 
> > > > > > Changes since v3:
> > > > > >    - Move all in_fence handling to the same VIRTGPU_EXECBUF_FENCE_FD_IN block
> > > > > Fwiw my suggestion was to explicitly document whether the IOCTL can
> > > > > support, simultaneously, IN and OUT fence.
> > > > 
> > > > Yes, that would be good.  Code looks like it is supposed to work, but
> > > > explicitly saying so in the commit message would be nice.
> > > 
> > > On it! Will send out a v5.
> > > 
> > > > 
> > > > Also: should we use separate fields for in/out fds?
> > > 
> > > I'm not sure I understand which fields you're referring to.
> > 
> > fence_in_fd & fence_out_fd in the ioctl struct (patch #2).
> 
> I had a look into this and how other drivers are doing it.
> msm[1] and etnaviv[2] seem to use the same dual-use variable.

Ok, lets do it the same way then.
What is the status of the userspace side of this?

cheers,
  Gerd